the studies of carbides formed during tempering of

18. - 20. 5. 2011, Brno, Czech Republic, EU
THE STUDIES OF CARBIDES FORMED DURING TEMPERING OF 217H12WF/D3 TOOL
STEEL AFTER AUSTENITIZING
STUDIE KARBIDŮ FORMOVANÝCH BĚHEM TEMPEROVÁNÍ NÁSTROJOVÉ OCELI
217H12WF/D3 PO AUSTENITIZACI
HRYNIEWICZ Tadeusz Prof., NYKIEL Tadeusz
Politechnika Koszalinska, FME, Koszalin, Poland, EU
The basic aim of this work was to establish the changes occurring in the tool steelconcerning carbides, their
formations and transformations, during tempering the steel underdifferent temperatures after its
austenitizing. The studies were carried out on steel of type217H12WF/AISI D3 hardened after austenitizing
at 1050 °C during 30 minutes andtempering at the temperatures from 200 °C up to 700 °C. It is known that in
the steel hardenedafter austenitizing at 1050 °C the process of carbides precipitation during tempering in
thetemperature range of 400-700 °C is distinctly higher than in temperatures up to 400 °C. Theidentification
studies of carbides were carried out by the method of electron diffraction fromthe extraction carbides
replicas.Based on the diffraction studies performed from the extraction replicas, using electronmicroscopy, it
was found that after 120-min tempering in the consecutive temperatures, thefollowing types of carbides
occur:200 °C ® e + c + Fe3C, 350 °C ® e + c + Fe3C500 °C ® c + M3C + M7C3, 600 °C ® c + M3C +
M7C3700 °C ® M3C + M7C3Apart from the higher mentioned carbides, there are also big primary carbides
and finesecondary ones M7C3 occurring, which have not been dissolved during austenitizing.Results of the
studies are to be helpful in solving the problems concerning adhesion andlife of super-hard layers coated
over the working surface of tools made of this type of steel, inthese also technological problems.
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